Field of the Invention
The invention relates to the field of illumination and, in particular, to a method for manufacturing a lamp-housing-type heat-sink, a lamp-housing-type heat-sink, and an LED lighting device.
Brief Description of the Related Art
Luminous efficiency is only around 10 lm/W for a traditional filament lamp, and about 30 lm/W for halide torches. Most of the electric energy is transformed into heat and dissipated, which causes a huge waste of electric energy. LED is a new semiconductor lighting technology, and the luminous efficiency of LED beads on the market can reach 120 lm/W and above. With excellent power supply and reasonable structure design, the luminous efficiency of an LED lamp can be over 90 lm/W. In this way, an LED lamp of 7 W to 9 W can replace a traditional filament lamp of 60 W and, thus, a lot of electric energy can be saved.
The common LED bulb, LED spotlight, and LED PAR lamp, etc. on the market are composed of a die-cast aluminum heat-sink, a semispherical diffuser or lens module, a circuit board with welded LED beads, an LED driving power, and a lamp base, etc. The circuit board is fixed on the die-cast aluminum heat-sink with a diffuser or lens module covered above, and there is a hollow cavity in the die-cast aluminum heat-sink in which LED driving power is installed.
In CN 201020220556.9, an LED bulb heat-sink and LED bulb are disclosed. The LED bulb heat-sink includes a heat transmission part on the top, a heat dissipation part in the side, and a positioning part in the bottom. The heat dissipation part includes several longitudinal heat radiation strips. The top ends of the heat radiation strips are connected with the heat transmission part, and the bottom ends form the positioning part. Spaces are reserved between the heat radiation strips. Although this provides a heat dissipation effect to some extent, it is economically inefficient for the non-integrated structure.
In CN 201020666630.X, a type of bulb is disclosed which includes a diffuser and lamp base that can be connected to the power, as well as a heat-sink set between the lamp base and the diffuser. A hollow cavity is set between the heat-sink for air flow, and spaces are also set at the two ends of the heat-sink for air flow. This invention is especially characterized by the hollow cavity and spaces in the heat-sink for air flow, which will take away the heat within the heat-sink to accelerate the heat dissipation.
In CN 201120086659.5, a type of LED bulb heat-sink is disclosed. The heat-sink is a one-piece structure with a main body and heat dissipation platform. The main body is hollow with several holes for thermal convection. The heat-sink is applied to energy-saving LED bulbs. The main body is an important part of the bulb appearance as well as the heat dissipation part of the LED. With materials of aluminum of high heat conductivity and the design of passive natural air flow heat dissipation, the heat dissipation efficiency of the lamp has been improved. Even with improved heat dissipation efficiency, this heat-sink is made of die-cast aluminum which is material consuming and leads to high weight and cost. The thermal conductivity of die-cast aluminum is about 88% and the heat dissipation efficiency is not satisfactory. In particular, this heat-sink includes an internal wall and an external wall. Strip holes for heat dissipation are arranged in parallel and radial directions on the external wall to form channels with multiple holes on the heat dissipation platform, so as to theoretically transmit the heat on the circuit board. However, since the circuit board is tightly close to the heat dissipation platform, the heat of the circuit board will be conducted to the space formed by the internal walls through the heat dissipation platform of die-cast aluminum and mutually affect heat from the power supply within the internal space.
In conclusion, the existing LED lighting devices have the following disadvantages:
First, the cost of the lamp housing, whether of traditional die-cast aluminum or aluminum of high heat conductivity as discussed above, is relatively high, accounting for over 30% of the whole. Moreover, the weight thereof is large with the conventional thickness, which will directly determine the weight of the whole LED bulb. This makes it difficult to decrease the weight of the whole LED bulb.
Second, the power supply of the lamp usually is confined within a plastic housing that is within the hollow cavity of the aluminum housing. The heat of the circuit board will be conducted to the hollow cavity of the aluminum housing, which will make the heat of the power supply and heat dissipation part affect each other and increase the internal temperature of the power supply. This will lead to power supply damage. Based on actual measurement, the temperature of the power supply can be over 80°.
Also, the housing includes an internal wall and an external wall, which makes the fabrication complex and increases weight and cost.
Additionally, the manufacturing of the housing of the existing LED lighting devices is complicated.